The present invention relates generally to radio frequency (RF) transponders such as radio frequency identification (RFID) transponders, and more specifically to a radio frequency identification transponder having a reflector.
Radio Frequency Identification has become an important information transfer system. From inventory management to automotive toll debiting, radio frequency identification systems have been utilized to transmit data in a variety of applications. RFID systems utilize an RF transmitter-receiver unit (base station or interrogator) to query an RF transponder, typically referred to as a tag, located at a distance. In some applications, the RF tag detects the interrogating signal and transmits a response signal comprising encoded data back to the interrogating unit. In this case, RFID systems have significant advantages e.g. in comparison to optical indicia readers. One example is the increased amount of data a radio frequency transponder may transmit. As another example, radio frequency transponders are not restricted to being read in a line-of-sight manner. A further unique advantage over other identification systems is that several RFID transponders may be read at one time.
One important consideration in a radio frequency identification system is the range at which the radio frequency transponder may be read. Past methods used to increase the range of a radio frequency transponder included increasing the power of the interrogating signal. This necessitated a greater use of energy. Increasing the energy of the interrogating signal may involve adding additional and more costly components to an RF transmitter-receiver unit. This may prove costly not only to manufacture, but also to utilize in its intended environment. Additionally, in some instances, it might be desirable to selectively orient the field-of-view of a radio frequency transponder relative to an interrogating source, receiver, or the like. For example, the radio frequency transponder might be relatively oriented so that it would respond to only one of two interrogating sources.
Consequently, it would be advantageous to provide a radio frequency transponder system with an increased effective range and/or a system that is capable of providing a radio frequency transponder with a selective field-of-view in a cost effective and efficient manner.
It is the intention of the present invention to provide an improved radio frequency transponder system with a reflector which increases the effective range of the radio frequency transponder so that the radio frequency transponder may be utilized over an increased distance, and/or a system capable of requiring selective relative orientation and/or providing selective reflective coupling of radiated energy during communication between system components.
A radio frequency identification transponder assembly in accordance with a first aspect of the invention includes a radio frequency transponder disposed next to a reflector. The reflector may comprise any sort of radio frequency reflective material. The reflector may be formed with the radio frequency transponder at its focus region so as to enhance the reception of transmitted energy (for power or information transfer), and/or the transmission of signal energy by the radio frequency transponder. In this manner, the reflector provides increased range of useful energy transfer between the radio frequency transponder and a base station or the like. For example, the reflector may increase the effective range by focusing an increased reception area of the reflector to a radio frequency transponder so as to increase the distance at which the radio frequency transponder may receive an interrogating signal or other energy, and/or transmit data.
In accordance with a second aspect of the present invention, a radio frequency transponder is disposed next to a reflector that may selectively orient the radio frequency transponder with respect to a base station or the like. For example, a reflector may be formed or positioned relatively so as to supply a radio frequency transponder with an interrogating signal from one source while excluding a signal from a second source.
In accordance with a third aspect of the present invention, a reflector is capable of selectively reflecting a radio frequency wave to and from a radio frequency transponder. In one example, the reflector is capable of selectively reflecting a radio wave so as to reflect a wave from one specific source to the transponder yet exclude transmissions from other sources.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention claimed. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention and together with the general description, serve to explain the principles of the invention.